Hydraulic Control Valve with Duplicate Workports and Integrated Actuator Oscillation Control Features

ABSTRACT

An example valve assembly includes a first workport fluidly coupled to a first actuator; a second workport fluidly coupled to the first actuator; a third workport fluidly coupled to a second actuator, wherein the third workport is fluidly coupled to the first workport via a first fluid passage; a fourth workport fluidly coupled to the second actuator, wherein the fourth workport is fluidly coupled to the second workport via a second fluid passage; and a spool axially movable in a bore within the valve assembly, wherein when the spool is shifted axially in a first axial direction, pressurized fluid is provided to the first workport and to the third workport via the first fluid passage, and when the spool is shifted axially in a second axial direction opposite the first axial direction, pressurized fluid is provided to the second workport and to the fourth workport via the second fluid passage.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority to U.S. Provisional patentapplication No. 62/789,596, filed on Jan. 8, 2019, and entitled“Hydraulic Control Valve with Duplicate Workports and IntegratedActuator Oscillation Control Features,” the entire contents of which areherein incorporated by reference as if fully set forth in thisdescription.

BACKGROUND

A hydraulic machine can have several hydraulic actuators configured toenable the machine to perform primary functions. For example, a wheelloader may have a hydraulic actuator configured to control movement of abucket, with the bucket being supported by a boom structure (e.g., twoarms coupling the bucket to the chassis of the wheel loader). Motion ofthe boom structure is enabled by one or more hydraulic actuators aswell.

A hydraulic system of such a hydraulic machine can include many complexfittings and complex plumbing (e.g., multiple hydraulic lines, hoses,and tubes) between the different components of the hydraulic system. Thehydraulic system can therefore be expensive and complicated to assemble,and comprises multiple potential leak points. As such, thisconfiguration can reduce reliability of the machine and increases thelikelihood of malfunction and machine downtime.

Therefore, it may be desirable to have configurations and componentsthat reduce plumbing complexity to reduce cost of the machine andenhances its reliability. It is with respect to these and otherconsiderations that the disclosure made herein is presented.

SUMMARY

The present disclosure describes implementations that relate to ahydraulic control valve with duplicate workports and integrated actuatoroscillation control features.

In a first example implementation, the present disclosure describes avalve assembly. The valve assembly includes: (i) a monoblock worksectionconfigured to control fluid flow to and from a first actuator and asecond actuator configured to be actuated in tandem, wherein themonoblock worksection comprises: (a) a first workport configured to befluidly coupled to a first chamber of the first actuator, (b) a secondworkport configured to be fluidly coupled to a second chamber of thefirst actuator, (c) a third workport configured to be fluidly coupled toa third chamber of the second actuator, wherein the third workport isfluidly coupled to the first workport via a first fluid passage withinthe monoblock worksection, and (d) a fourth workport configured to befluidly coupled to a fourth chamber of the second actuator, wherein thefourth workport is fluidly coupled to the second workport via a secondfluid passage within the monoblock worksection; and (ii) a spool axiallymovable in a bore within the monoblock worksection, wherein: (a) whenthe spool is shifted axially in a first axial direction within the bore,pressurized fluid is provided from a source of pressurized fluid to thefirst workport and to the third workport via the first fluid passage soas to drive the first actuator and the second actuator in tandem in afirst direction, and (b) when the spool is shifted axially in a secondaxial direction within the bore opposite the first axial direction,pressurized fluid is provided from the source of pressurized fluid tothe second workport and to the fourth workport via the second fluidpassage so as to drive the first actuator and the second actuator intandem in a second direction opposite the first direction.

In a second example implementation, the present disclosure describes avalve assembly. The valve assembly includes: (i) a first worksectionconfigured to control fluid flow to and from a first actuator and asecond actuator configured to be actuated in tandem, wherein the firstworksection comprises: (a) a first workport configured to be fluidlycoupled to a first chamber of the first actuator, (b) a second workportconfigured to be fluidly coupled to a second chamber of the firstactuator; (ii) a second worksection mounted to the first worksection,wherein the second worksection comprises: (a) a third workportconfigured to be fluidly coupled to a third chamber of the secondactuator, wherein the third workport is fluidly coupled to the firstworkport via a first fluid conduit, and (b) a fourth workport configuredto be fluidly coupled to a fourth chamber of the second actuator,wherein the fourth workport is fluidly coupled to the second workportvia a second fluid conduit; and (iii) a spool axially movable in a borewithin the first worksection, wherein: (a) when the spool is shiftedaxially in a first axial direction within the bore, pressurized fluid isprovided from a source of pressurized fluid to the first workport and tothe third workport via the first fluid conduit so as to drive the firstactuator and the second actuator in tandem in a first direction, and (b)when the spool is shifted axially in a second axial direction within thebore opposite the first axial direction, pressurized fluid is providedfrom the source of pressurized fluid to the second workport and to thefourth workport via the second fluid conduit so as to drive the firstactuator and the second actuator in tandem in a second directionopposite the first direction.

In a third example implementation, the present disclosure describes ahydraulic system. The hydraulic system includes a source of pressurizedfluid; a tank; a first actuator having a first chamber and a secondchamber; a second actuator having a third chamber and a fourth chamber,and configured to be actuated in tandem with the first actuator; and avalve assembly fluidly coupled to the source of pressurized fluid, thetank, the first actuator, and the second actuator. The valve assemblyfurther includes: (i) a first workport fluidly coupled to the firstchamber of the first actuator; (ii) a second workport fluidly coupled tothe second chamber of the first actuator; (iii) a third workport fluidlycoupled to the third chamber of the second actuator, wherein the thirdworkport is fluidly coupled to the first workport via a first fluidpassage; (iv) a fourth workport fluidly coupled to the fourth chamber ofthe second actuator, wherein the fourth workport is fluidly coupled tothe second workport via a second fluid passage; and (v) a spool axiallymovable in a bore within the valve assembly, wherein: (a) when the spoolis shifted axially in a first axial direction within the bore,pressurized fluid is provided from the source of pressurized fluid tothe first workport and to the third workport via the first fluid passageso as to drive the first actuator and the second actuator in tandem in afirst direction, and (b) when the spool is shifted axially in a secondaxial direction within the bore opposite the first axial direction,pressurized fluid is provided from the source of pressurized fluid tothe second workport and to the fourth workport via the second fluidpassage so as to drive the first actuator and the second actuator intandem in a second direction opposite the first direction.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects,implementations, and features described above, further aspects,implementations, and features will become apparent by reference to thefigures and the following detailed description.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates a perspective view of a valve assembly of a hydraulicsystem, in accordance with an example implementation.

FIG. 2 illustrates a perspective view of the valve assembly shown inFIG. 1 from an opposite point of view, in accordance with an exampleimplementation.

FIG. 3 illustrates a cross-sectional view of a worksection, inaccordance with an example implementation.

FIG. 4 illustrates a partial perspective cross-sectional view of thevalve assembly of FIGS. 1-2 showing two worksections formed as amonoblock worksection, in accordance with an example implementation.

FIG. 5 illustrates a partial perspective cross-sectional view of thevalve assembly of FIGS. 1-2 showing two worksections formed as separatecastings that interface to form a fluid conduit, which fluidly couplesworkports of the two worksections, in accordance with an exampleimplementation.

FIG. 6 illustrates a partial perspective cross-sectional view of thevalve assembly of FIGS. 1-2 showing two worksections formed as separatecastings with a tube disposed within a fluid conduit that fluidlycouples workports of the two worksections, in accordance with an exampleimplementation.

FIG. 7 illustrates a perspective view of the tube of FIG. 6, inaccordance with an example implementation.

FIG. 8 illustrates a perspective view of a worksection having a firsttube and a second tube mounted thereto, in accordance with an exampleimplementation.

FIG. 9 illustrates a perspective cross-sectional view of a valveassembly showing the two tubes of FIG. 8, in accordance with an exampleimplementation.

FIG. 10 illustrates a cutaway perspective view of a worksection showingoscillation control features, in accordance with an exampleimplementation.

FIG. 11 is a flowchart of a method for operating a hydraulic system, inaccordance with an example implementation.

DETAILED DESCRIPTION

Hydraulic machinery (e.g., a wheel loader) includes a hydraulic systemconfigured to control fluid flow to hydraulic actuators. Particularly,the hydraulic system can include a source of fluid, such as a pump,configured to provide fluid flow at a particular pressure level to thehydraulic actuators through a valve to cause the hydraulic actuators tomove.

In certain applications, fluid flow in a hydraulic machine can becontrolled using sectional control valves. A sectional control valve orvalve assembly can include a plurality of separate cast and machinedmetal valve worksections. Each worksection can include internal fluidpassages, external ports, and valve bores.

The valve bores can include a spool bore in which a spool is slidablydisposed. Each worksection can be configured to control flow of fluid toand from a hydraulic actuator of the hydraulic machine. For example, inthe case of a wheel loader, the valve can have one worksection tocontrol fluid flow to and from a bucket actuator and another worksectionto control fluid flow to and from boom actuators.

A large-bucket wheel loader machine can have a pair of hydraulicactuators for the boom. In this case, fluid provided from the valve tothe boom actuators is split evenly between the two boom actuators to beable to drive the boom actuators in tandem. Further, some wheel loadersinclude boom actuator oscillation control features to keep the machinestable while driving across uneven ground with a heavy load in thebucket. The boom actuator oscillation control features involve using aseparate valve that is in fluid communication with the main valve thatprovides fluid to the boom actuator. The separate valve can be fluidlycoupled to an accumulator to dampen or absorb oscillations of the boomactuator.

Conventional machines have complex ‘T’ fittings that split and send theflow to the separate valve, and then to the boom actuators and theaccumulator. Such configuration involves many fittings and complexplumbing (e.g., multiple hydraulic lines, hoses, and tubes) between thedifferent components of the hydraulic system. The hydraulic system istherefore expensive and complicated to assemble, and comprises multiplepotential leak points. As such, this configuration can reducereliability of the machine and increases the likelihood of malfunctionand machine downtime. Therefore, it may be desirable to have a valvethat reduce plumbing complexity to reduce cost of the machine andenhances its reliability.

Disclosed herein are hydraulic systems, valve sections, and valveassemblies that, among other features, provide duplicate workports toprovide fluid to a pair of actuators without using complex fittings andplumbing. Further, the hydraulic systems, valve sections, and valveassemblies disclosed herein integrate actuator oscillation controlfeatures in the valve assembly to reduce plumbing complexity. This way,complexity of the hydraulic system can be reduced, and thus cost can bereduced while enhancing reliability.

FIG. 1 illustrates a perspective view of a valve assembly 100 of ahydraulic system 200, and FIG. 2 illustrates a perspective view of thevalve assembly 100 from an opposite point of view, in accordance with anexample implementation. FIGS. 1 and 2 are described together.

The valve assembly 100 can be included in the hydraulic system 200,which can be configured to control implements of a vehicle. A wheelloader is used herein as an example vehicle to illustrate theconfiguration and operation of the valve assembly 100; however, thefeatures of the valve assembly 100 can be used with other machine orvehicle types.

The hydraulic system 200 of the wheel loader can include a source 202 offluid. The source can, for example, be a pump that operates as aload-sensing source of pressurized hydraulic fluid, such as aload-sensing variable-displacement pump.

The valve assembly 100 has an inlet section 102, a worksection 104, aworksection 106, a worksection 108, and an outlet section 110. Theillustrated valve assembly is provided for illustration purposes, an inother examples, more or fewer worksections can be used.

The inlet section 102, the worksections, 104, 106, 108, and the outletsection 110 can be coupled together by fasteners (e.g., tie rods such astie rods 111A, 111B, 111C, and 111D shown in FIG. 1) to provide anassembly of the valve sections 102-110. For example, the worksections104, 106, and 108 can be positioned adjacent one another between theinlet section 102 and the outlet section 110 of the valve assembly 100.

Assuming the hydraulic system 200 is for a wheel loader, the worksection104 can be configured to control fluid flow to and from a bucketactuator 204, whereas the worksections 106, 108 can be configured tocontrol fluid flow to and from a pair of boom actuators 206, 208. Theboom actuators 206, 208 are actuated in tandem (e.g., in the samedirection) to lift or lower the bucket of the wheel loader. Further, theworksection 108 integrates oscillation control features within the valveassembly 100 as described below with respect to FIG. 10.

Each of the actuators 204, 206, 208 is depicted in as a linear actuatorhaving a cylinder and a piston slidably accommodated in the cylinder.The piston includes a piston head and a rod extending from the pistonhead along a central longitudinal axis direction of the cylinder. Therod is coupled to a respective implement (e.g., coupled to the bucket ofthe wheel loader). The piston head divides the inner space of thecylinder into a first chamber and a second chamber. As an example, thesecond chamber can be the chamber that has the rod of the piston and cantherefore be referred to as the rod side or the rod chamber. The firstchamber can be referred to as the cap side or the head side.

As shown in FIG. 1, the worksection 104 has a valve section body 112.Similarly, the worksection 106 has a valve section body 114, and theworksection 108 has a valve section body 115. The valve section bodies112, 114, and 115 can, for example, be made as metal castings.

The source 202 of fluid of the hydraulic system 200 is configured toreceive fluid from a reservoir or tank 210 to provide pressurized fluidto the valve assembly 100. The tank 210 can be configured to storehydraulic fluid at a low pressure, e.g., 0-70 pounds per square inch(psi).

The valve assembly 100, and particularly, the inlet section 102, caninclude a main pressure relief valve 113 to protect components of thehydraulic system from elevated pressure levels that exceed a particularthreshold pressure level (e.g., 5000 psi). If a pressure level of thefluid in the hydraulic system exceeds the threshold pressure level, themain pressure relief valve 113 opens a fluid path from the pump to thetank.

The source 202 of fluid can be fluidly coupled to an inlet port 116disposed in the inlet section 102 of the valve assembly 100 such thatoutput fluid flow from the source 202 is received at the inlet port 116.The output fluid flow of the pump is then provided to the valve sectionsof the valve assembly 100.

The tank 210 is fluidly coupled to a tank port 118 also disposed in theinlet section 102 of in the valve assembly 100. Fluid can be allowed toreturn to the tank 210 from the valve sections of the valve assembly 100via a tank flow passage and through the tank port 118.

As shown in FIG. 1, the tank port 118 and the inlet port 116 arevertically-stacked in different planes. Particularly, in the exampleimplementation shown in FIG. 1, the tank port 118 is disposed verticallyabove the inlet port 116 in the inlet section 102 of the valve assembly100. This configuration can be beneficial if the valve assembly 100 isused, for example, to control an articulated hydraulic machine orvehicle, e.g., an articulated wheel loader. An articulated vehicle is avehicle that is formed as two separate pieces. The two separate piecesare joined at a central point, and the articulated vehicle swivels atthe central point. This configuration enables the articulated vehicle tomaneuver in tight spaces. When the articulated vehicle swivels, however,hoses and hydraulic lines that communicate fluid to and from a valveassembly controlling operation of the articulated vehicle may rubagainst each other and damage may occur. The configuration of the valveassembly 100 shown in FIG. 1 can preclude such damage from occurring.Particularly, the valve assembly 100 can be disposed at a centrallocation of the articulated vehicle. Further, the vertical stacking ofthe tank port 118 and the inlet port 116 causes a hose or hydraulic linethat connects the source 202 to the inlet port 116 to be disposed in aplane that is different from a respective plane of a hose or hydraulicline that connects the tank port 118 to the tank 210. As a result, thehoses do not rub against each other when the articulated vehicle swivelsand damage thereto may be precluded.

The worksection 104 includes a first workport 120 and a second workport121. The workport 120 can, for example, be fluidly coupled to a firstchamber (head side) of the bucket actuator 204, whereas the workport 121can be fluidly coupled to a second chamber (rod side) of the bucketactuator 204.

Similarly, the worksection 106 includes a first workport 122 and asecond workport 123. The workport 122 can, for example, be fluidlycoupled to a first chamber (head side) of the first boom actuator 206,whereas the workport 123 can be fluidly coupled to a second chamber (rodside) of the first boom actuator 206. The worksection 108 includes afirst workport 124 and a second workport 125. The workport 124 can, forexample, be fluidly coupled to a first chamber (head side) of the secondboom actuator 208, whereas the workport 125 can be fluidly coupled to asecond chamber (rod side) of the second boom actuator 208. Hydrauliclines are represented schematically as dashed lines in FIG. 1. Further,hydraulic lines connecting the workports 120-125 to their respectiveactuators are not shown in FIG. 1 to reduce visual clutter in thedrawing.

In conventional systems, a single worksection is used to control fluidto and from the pair of boom actuators where fluid is split and sent toa separate, external valve that performs oscillation control, and thenon to the boom actuators and an accumulator. With the configuration ofthe valve assembly 100, however, the worksection 108 duplicates theworkports of the worksection 106 as described in details below. Thisway, fluid is split internally to be provided through the workports ofthe worksection 106 to the first boom actuator 206, and provided throughworkports of the worksection 108 to the second boom actuator 208.Further, the worksection 108 is configured to include the oscillationcontrol components and features.

The valve assembly 100 can include workport relief valves to protect thehydraulic actuators from high pressure levels. For example, theworksection 104 can include a first workport relief valve 105A fluidlycoupled to the workport 121 to protect the rod side of the bucketactuator 204 and a second workport relief valve 105B fluidly coupled tothe workport 120 to protect the head side of the bucket actuator 204. Inexamples, the worksection 106 can include an anti-cavitation valve 105Cfluidly coupled to the workport 123 and the workport 125 to allow fluidfrom the tank 210 to flow to the rod sides of the boom actuators 206,208 if pressure level therein drops below a threshold pressure level(e.g., 50 psi) as pistons of the boom actuators 206, 208 retract at ahigh speed.

Each of the worksections 104, 106 includes a respective spool asdescribed below with respect to FIG. 3. The spool can be actuated ineither direction via various types of mechanisms. As an example forillustration, a pilot valve 126 and a corresponding pilot valve on theother side of the worksection 104 can be solenoid-operated and can beused to actuate or move the spool in a spool bore disposed with theworksection 104. Similarly, a pilot valve 128 (shown in FIG. 3) and acorresponding pilot valve (pilot valve 129 shown in FIGS. 2, 3) on theother side of the worksection 106 can be solenoid-operated and can beused to actuate or move the spool in a spool bore disposed with theworksection 106. However, other configurations of pilot valves that aremanually, hydraulically, or pneumatically actuated can be used. Thepilot valves 126, 128, 129 are depicted and described herein assolenoid-operated as an example for illustration only.

The pilot valves 126, 128, 129 are configured to receive a pilot fluidsignal, such that when a pilot valve of the pilot valves 126, 128, 129is actuated by an electric signal, the actuated pilot valve provides thepilot fluid signal or enables communication of the pilot fluid signal toan end cap disposed at a respective end of the spool. The fluid in theend cap applies a force on the spool in a respective axial directioncausing the spool to shift in the spool bore.

Referring to FIG. 1, to provide the pilot fluid signal to the pilotvalves 126, 128, 129, the inlet section 102 of the valve assembly 100includes a pressure reducing valve 130 that is fluidly coupled to theinlet port 116 via a hydraulic passage within the inlet section 102. Thepressure reducing valve 130 is configured to receive the pressurizedfluid provided by the source 202 and generate the pilot fluid signal forthe pilot valves 126, 128, 129. Particularly, the pressure reducingvalve 130 is configured to reduce pressure level of the pressurizedfluid provided by the source 202 (which can have a high pressure levelsuch as 4000 psi) to a particular lower pressure level, such as 600 psi.Other techniques can be used to generate the pilot fluid signal. Forexample, the pilot fluid signal can be provided externally to the valveassembly 100 through a particular port in one of the valve sections(e.g., the inlet section 102). In another example, the pilot fluidsignal can be provided from the source 202 or from another source (e.g.,another pump) configured to generate the pilot fluid signal. Generatingthe pilot fluid signal by the pressure reducing valve 130 is used hereinas an example for illustration.

The pilot fluid signal generated by the pressure reducing valve 130 canthen flow to a pilot-enable valve 134 disposed in the inlet section 102.The pilot-enable valve 134 is actuatable by a solenoid 135. When thepilot-enable valve 134 is actuated (e.g., an electric signal is providedto the solenoid 135), the pilot-enable valve 134 operates in apilot-enable state.

When the pilot-enable valve 134 is unactuated (e.g., no electric signalis provided to the solenoid 135), the pilot-enable valve 134 operates ina pilot-disable state. When the pilot-enable valve 134 operates in thepilot-disable state, the pilot fluid signal generated by the pressurereducing valve 130 is blocked. Thus, when the pilot-enable valve 134 isunactuated, no pilot fluid signal is provided to the pilot valves 126,128, 129. In this state, the valve assembly 100 operates in a safetymode and the spools (e.g., the spool 148 of the worksection 106) are notactuatable. As such, the pilot-enable valve 134 facilitates safeoperation of the valve assembly 100. Particularly, the pilot-enablevalve 134 enables shifting of the spools (e.g., the spool 148) in theworksections 104, 106 when the pilot-enable valve 134 is energized oractuated, but disables shifting of the spools when the pilot-enablevalve 134 is de-energized or de-actuated

FIG. 3 illustrates a cross-sectional view of the worksection 106, inaccordance with an example implementation. Referring to FIGS. 1, 2, 3together, when the solenoid 135 is energized and the pilot-enable valve134 operates in the pilot-enable state, the pilot-enable valve 134enables communication of the pilot fluid signal to the worksections 104,106. Particularly, the pilot fluid signal generated by the pressurereducing valve 130 flows through the pilot-enable valve 134. The pilotfluid signal then flows through pilot fluid passages formed ofcross-drilled passages in the inlet section 102 and the worksections104, 106 to provide the pilot fluid signal to the pilot valves 126, 128,129.

For example, the inlet section 102 may include cross-drilled passagesthat communicate the pilot fluid signal to pilot openings in the inletsection 102, and the pilot openings of the inlet section 102 can bealigned with corresponding pilot openings in the worksections 104, 106,such as pilot openings 141A, 141B of the worksection 106 (shown in FIG.3), to form a pilot fluid passage and enable the pilot fluid signal totraverse the valve assembly 100. The pilot fluid passage is furtherconnected through cross-drilled passages in the worksections 104, 106 tothe pilot valves 126 (and the corresponding pilot valve on the otherside of the worksection 104), 127, 128.

Referring to FIG. 3, if the pilot valve 128 is actuated, the pilot valve128 reduces a pressure level of the pilot fluid signal (e.g., from 600psi to a pressure level value between 200 psi and 460 psi proportionalto an electric command signal to the pilot valve 128) and allows thepilot fluid signal to flow through passage 144 to end cap chamber 146within end cap 147A. The pilot fluid then applies a force on a spool 148disposed in a spool bore in the valve section body 114 of theworksection 106 to move the spool 148 axially in a first direction(e.g., to the right in FIG. 3).

Conversely, if the pilot valve 129 is actuated, the pilot valve 129reduces a pressure level of the pilot fluid signal (e.g., from 600 psito a pressure level value between 200 psi and 460 psi proportional to anelectric command signal to the pilot valve 129) and allows the pilotfluid signal to flow through passage 149 to end cap chamber 150 withinend cap 147B. The pilot fluid then applies a force on the spool 148 tomove the spool 148 axially in a second direction (e.g., to the left inFIG. 3), opposite the first direction.

As illustrated in FIG. 3, the worksection 106 further includes drainopenings 151, 152. The drain openings 151, 152 fluidly couple the pilotvalves 128, 129, respectively, through cross-drilled passages in thevalve assembly 100 (not shown in the cross-sectional view of FIG. 3) toa drain passage. The drain passage can operate as a dedicated drainconnection for the pilot valves 128, 129. The drain passage fluidlycouples the pilot valves 128, 129 to a drain port that is separate fromthe tank port 118. As such, the drain passage is separate from tank flowpassages, and is thus not exposed to elevated return flow pressure inthe tank flow passages and the tank 210. The worksection 104 can beconfigured with and pilot and drain openings similar to the worksection106, and operation of the pilot valve 126 and the corresponding pilotvalve on the opposite side of the worksection 104 can be configured tobe similar to operation of the pilot valves 128, 129.

Movement of the spool 148 of the worksection 106 causes fluid to bedirected to and from the workports 122, 123, which are fluidly coupledto the head and rod sides, respectively, of the first boom actuator 206.Particularly, movement of the spool 148 within a respective spool boredefines one or more variable area metering orifices that provide meteredflow across the spool 148 depending upon the spool position. Forexample, the spool 148 has a plurality of annular grooves or axialnotches that cooperate with internal surfaces of the valve section body114 to define metering orifices. A position of the spool may be adjustedwith respect to the valve section body 114 to variably adjust the areaof the metering orifices.

Fluid from the inlet port 116 is provided to an inlet passage 160 shownin FIG. 3. Assuming that the spool 148 moves to the right due toactuation of the pilot valve 128, a variable area metering orifice canbe formed to allow fluid to flow from the inlet passage 160 to a meteredflow chamber 162. The worksection 106 includes a pressure compensatorvalve 166 located downstream from the metered flow chamber 162. Thepressure compensator valve 166 is configured to maintain a predeterminedpressure drop across a variable metering orifice formed when the spool148 is moved axially regardless of the load experienced by the boomactuator 206, 208.

The fluid in the metered flow chamber 162 can then push a poppet 164 ofthe pressure compensator valve 166 and flow to a regulated flow passage168. Another variable area metering orifice forms as the spool 148shifts to the right to allow fluid to flow from the regulated flowpassage 168 to a workport fluid passage 170, and then to the workport123, which is fluidly coupled to the rod side of the first boom actuator206. As a result, a piston of the first boom actuator 206 retracts(e.g., moves downward in FIG. 3). Fluid exiting or forced out of thehead side of the first boom actuator 206 as the piston retracts iscommunicated to the workport 122 and then to a workport fluid passage172. Another variable area metering orifice forms as the spool 148shifts to the right to allow fluid to flow from the workport fluidpassage 172 to a tank passage 174, which can be fluidly coupled to thetank 210.

Conversely, if the spool 148 moves to the left due to actuation of thepilot valve 129, a variable area metering orifice can be formed to allowfluid to flow from the inlet passage 160 to the metered flow chamber162. The fluid in the metered flow chamber 162 can then push the poppet164 of the pressure compensator valve 166 and flow to the regulated flowpassage 168. Another variable area metering orifice forms as the spool148 shifts to the left to allow fluid to flow from the regulated flowpassage 168 to the workport fluid passage 172, and then to the workport122, which is fluidly coupled to the head side of the first boomactuator 206. As a result, the piston of the first boom actuator 206extends (e.g., moves upward in FIG. 3). Fluid exiting or forced out ofthe rod side of the first boom actuator 206 as the piston extends iscommunicated to the workport 123 and then to the workport fluid passage170. Another variable area metering orifice forms as the spool 148shifts to the left to allow fluid to flow from the workport fluidpassage 172 to a tank passage 176, which can be fluidly coupled to thetank 210.

In conventional systems, fluid provided to the workport 122 or theworkport 123 is split via a complex ‘T’ fitting to be provided to thesecond boom actuator 208 so as to drive the boom actuators 206, 208together in tandem. Fluid can further be split via the ‘T’ fitting andprovided to a separate valve configured to control oscillations of theboom actuators 206, 208 as the wheel loader moves.

The valve assembly 100, however, is configured to have the worksection108 coupled to or integrated with the worksection 106 so as to implementan internal flow split and avoid using complex fittings and plumbing.Specifically, the workport 124 of the worksection 108 is fluidly coupledto the workport 122 of the worksection 106 such that fluid provided tothe workport 122 of the worksection 106 is split internally and providedalso to the workport 124 of the worksection 108. This way, fluidprovided to the workport 122 to be provided to the head side of thefirst boom actuator 206 is internally split and provided to the workport124 to be provided to the head side of the second boom actuator 208without using complex fittings.

Similarly, the workport 125 of the worksection 108 is fluidly coupled tothe workport 123 of the worksection 106 such that fluid provided to theworkport 123 of the worksection 106 is split internally and providedalso to the workport 125 of the worksection 108. This way, fluidprovided to the workport 123 to be provided to the rod side of the firstboom actuator 206 is internally split and provided to the workport 125to be provided to the rod side of the second boom actuator 208 withoutusing complex fittings.

Further, the worksection 108 is configured to include oscillationcontrol features and components. This way, the worksection 108 providesfluid to and receive fluid from the second boom actuator 108 as well asinclude the oscillation control components. With this configuration ofthe valve assembly 100 may reduce plumbing complexity of the hydraulicsystem 200 and enhances reliability.

The worksection 108 can be coupled to the worksection 106 in severalways. For example, the worksections 106, 108 can be formed as amonoblock (e.g., a single manifold or casting) having the four workports122, 123, 124, 125 formed therein and fluidly coupled via internalpassages. In other words, the valve section bodies 114, 115 areconfigured as one casting. This configuration is shown in FIG. 4.

Alternatively, the worksections 106, 108 can be formed as separatecastings and are stacked together to align internal passages thereof andfluidly couple the workport 122 to the workport 124 and fluidly couplethe workport 123 to the workport 125. This configuration can beimplemented using face seals between the worksections 106, 108 as shownin FIG. 5 or using tubes that fluidly coupled respective internalpassages in the worksections 106, 108 as illustrated in FIGS. 6, 7, 8,and 9.

FIG. 4 illustrates a partial perspective cross-sectional view of thevalve assembly 100 showing the worksections 106, 108 formed as amonoblock worksection 400, in accordance with an example implementation.As depicted in FIG. 4, the worksections 106, 108 are integrated into themonoblock worksection 400 configured as a single casting rather than twoseparate castings.

The monoblock worksection 400 includes a fluid passage 402 that fluidlycouples the workport fluid passage 172 (which is fluidly coupled to theworkport 122) to a workport fluid passage 404, which is fluidly coupledto the workport 124. When the pistons of the boom actuators 206, 208 areto be extended (the spool 148 moves to the left in FIG. 3), pressurizedfluid is provided to the workport fluid passage 172 then to the workport122 to be provided to the head side of the first boom actuator 206. Atthe same time, the pressurized fluid is split via the fluid passage 402and provided to the workport fluid passage 404, then to the workport124, and then to the head side of the second boom actuator 208 so as toextend the boom actuators 206, 208 in tandem.

When the pistons of the boom actuators 206, 208 are to be retracted (thespool 148 moves to the right in FIG. 3), fluid forced out of the headsides of the boom actuators 206, 208 is provided to the workports 122,124. Fluid provided to the workport 122 is communicated to the workportfluid passage 172, and fluid provided to the workport 124 is alsocommunicated to the workport fluid passage 172 via the workport fluidpassage 404 and the fluid passage 402. This way, fluid is combined inthe workport fluid passage 172 and provided to the tank passage 174 (seeFIG. 3) and then to the tank 210 as described above with respect to FIG.3. With the configuration of FIG. 4, fluid to be provided to or receivedfrom the workports 122, 124 is split or combined without using complexfitting or plumbing.

Although not shown in the cross-sectional view of FIG. 4, the workports123, 125 are also internally fluidly coupled to each other via fluidpassages in the worksection 108 that are similar the fluid passage 402and the workport fluid passage 404. This way, the workport 125 of theworksection 108 can be fluidly coupled to the workport fluid passage 170of the worksection 106.

In another example implementation, the worksections 106, 108 can beseparate castings that interface with each other or are stacked adjacentto each other to form conduits that couple the workports to each other.FIG. 5 illustrates a partial perspective cross-sectional view of thevalve assembly 100 showing the worksections 106, 108 formed as separatecastings that interface to form a fluid conduit 500, which fluidlycouples the workports 122, 124, in accordance with an exampleimplementation.

As depicted in FIG. 5, the worksections 106, 108 are stacked adjacent toeach other such that a fluid passage 502 in the worksection 106 isaligned with a corresponding fluid passage 504 in the worksection 108 toform the fluid conduit 500. The fluid conduit 500 fluidly couples theworkport fluid passage 172 (which is fluidly coupled to the workport122) of the worksection 106 to a workport fluid passage 506 (which isfluidly coupled to the workport 124) of the worksection 108.

When the pistons of the boom actuators 206, 208 are to be extended (thespool 148 moves to the left in FIG. 3), pressurized fluid is provided tothe workport fluid passage 172 then to the workport 122 to be providedto the head side of the first boom actuator 206. At the same time, thepressurized fluid is split via the fluid conduit 500 and provided to theworkport fluid passage 506, then to the workport 124 and the head sideof the second boom actuator 208 so as to extend the boom actuators 206,208 in tandem.

When the pistons of the boom actuators 206, 208 are to be retracted (thespool 148 moves to the right in FIG. 3), fluid forced out of the headsides of the boom actuators 206, 208 is provided to the workports 122,124. Fluid provided to the workport 122 is communicated to the workportfluid passage 172, and fluid provided to the workport 124 is alsocommunicated to the workport fluid passage 172 via the workport fluidpassage 506 and the fluid conduit 500. This way, fluid is combined inthe workport fluid passage 172 and provided to the tank passage 174 (seeFIG. 3) and then to the tank 210 as described above with respect to FIG.3. With the configuration of FIG. 5, fluid to be provided to or receivedfrom the workports 122, 124 is split or combined without using complexfitting or plumbing.

The worksection 106 can have an annular groove 508 formed in an end faceof the worksection 106 that faces the worksection 108. The annulargroove 508 is formed about or around the fluid passage 502 and fluidconduit 500.

The annular groove 508 is configured to receive a face seal 510 therein.When the valve assembly 100 is assembled (e.g., via the tie rods111A-111D shown in FIGS. 1-2) and the worksection 106, 108 are forcedagainst each other, the face seal 510 is squeezed such that sealingsurfaces of the face seal 510 are normal to a longitudinal axis of theface seal 510 and the fluid conduit 500. The face seal 510 is thusconfigured to prevent leakage in the radial direction between theworksections 106, 108 as fluid flows through the fluid conduit 500. Assuch, fluid flowing through the fluid conduit 500 does not leak at theinterface between the worksections 106, 108 to an external environmentof the valve assembly 100. The face seal 510 can include any type offace seal such as O-ring, E-ring, C-ring, gasket, end-face mechanicalseal, floating seal, due-cone seal, toric seal, etc.

Although not shown in the cross-sectional view of FIG. 5, the workports123, 125 are also internally fluidly coupled to each other via fluidpassages and a fluid conduit in the worksections 106, 108 that aresimilar the fluid passages 502, 504 forming a fluid conduit similar tothe fluid conduit 500. This way, the workport 125 of the worksection 108can be fluidly coupled to the workport fluid passage 170 of theworksection 106.

In another example implementation, rather than using the face seal 510,a tube can be placed in the fluid conduit 500 at the interface betweenthe worksection106 and the worksection 108, and the tube can have radialseals so as to preclude leakage between the worksections 106, 108. Thisconfiguration is described next with respect to FIGS. 6-9.

FIG. 6 illustrates a partial perspective cross-sectional view of thevalve assembly 100 showing the worksections 106, 108 formed as separatecastings with a tube 600 disposed within the fluid conduit 500 thatfluidly couples the workports 122, 124, in accordance with an exampleimplementation. Similar to the implementation in FIG. 5, in FIG. 6 theworksections 106, 108 are stacked adjacent to each other to form thefluid conduit 500. Additionally, the tube 600 is disposed in the fluidconduit 500, and the tube 600 is hollow such that the hollow interiorspace of the tube 600 is part of the fluid conduit 500.

The worksection 106 has a counterbore 602 that forms an annular shoulderagainst which the tube 600 rests, i.e., the tube 600 interfaces with theannular shoulder. Similarly, the worksection 108 has a counterbore 604that forms an annular shoulder against which the tube 600 rests or withwhich the tube 600 interfaces. As such, the tube 600 is secured betweenthe annular shoulder of the counterbore 602 and the respective annularshoulder of the counterbore 604.

FIG. 7 illustrates a perspective view of the tube 600, in accordancewith an example implementation. As shown in FIG. 7, the tube 600 iscylindrical in shape and is hollow. The interior space of the tube 600forms a channel 700 that is a portion of or is comprised in the fluidconduit 500 to allow fluid communication between the worksections 106,108 therethrough.

The tube 600 has a first annular groove 702 formed in an exteriorperipheral surface of the tube 600. The first annular groove 702 isconfigured to receive a first radial seal 704 (e.g., an 0-ring) therein.Referring to FIGS. 6 and 7 together, the first radial seal 704 isdisposed between the interior peripheral surface of the counterbore 602and the exterior peripheral surface of the tube 600. Pressurized fluidprovided to or from the workport fluid passage 172 through the fluidconduit 500 (or the channel 700) squeezes or applies compression on anoutside diameter and an inside diameter of the first radial seal 704.The first radial seal 704 thus seals an annular space between theinterior peripheral surface of the counterbore 602 and the exteriorperipheral surface of the tube 600. As such, fluid flowing through thefluid conduit 500 does not leak through the annular space between theinterior peripheral surface of the counterbore 602 and the exteriorperipheral surface of the tube 600 to an external environment of thevalve assembly 100.

Similarly, the tube 600 has a second annular groove 706 formed in theexterior peripheral surface of the tube 600. The second annular groove706 is configured to receive a second radial seal 708 (e.g., an 0-ring)therein. Referring to FIGS. 6 and 7 together, the second radial seal 708is disposed between the interior peripheral surface of the counterbore604 and the exterior peripheral surface of the tube 600. Pressurizedfluid provided to or from the workport fluid passage 506 through thefluid conduit 500 (or the channel 700) squeezes or applies compressionon an outside diameter and an inside diameter of the second radial seal708. The second radial seal 708 thus seals an annular space between theinterior peripheral surface of the counterbore 604 and the exteriorperipheral surface of the tube 600. As such, fluid flowing through thefluid conduit 500 does not leak through the annular space between theinterior peripheral surface of the counterbore 604 and the exteriorperipheral surface of the tube 600 to an external environment of thevalve assembly 100.

With this configuration, the channel 700 of tube 600 fluidly couples theworkport fluid passage 172 (which is fluidly coupled to the workport122) of the worksection 106 to the workport fluid passage 506 (which isfluidly coupled to the workport 124) of the worksection 108. When thepistons of the boom actuators 206, 208 are to be extended, pressurizedfluid is provided to the workport fluid passage 172 then to the workport122 to be provided to the head side of the first boom actuator 206. Atthe same time, the pressurized fluid is split via the channel 700 of thetube 600 and provided to the workport fluid passage 506, then to theworkport 124 and the head side of the second boom actuator 208 so as toextend the boom actuators 206, 208 in tandem.

When the pistons of the boom actuators 206, 208 are to be retracted,fluid forced out of the head sides of the boom actuators 206, 208 isprovided to the workports 122, 124. Fluid provided to the workport 122is communicated to the workport fluid passage 172, and fluid provided tothe workport 124 is also communicated to the workport fluid passage 172via the workport fluid passage 506 and the channel 700. This way, fluidis combined in the workport fluid passage 172 and provided to the tankpassage 174 (see FIG. 3) and then to the tank 210 as described abovewith respect to FIG. 3. With the configuration of FIG. 6, fluid to beprovided to or received from the workports 122, 124 is split or combinedwithout using complex fitting or plumbing.

The workports 123, 125 are also internally fluidly coupled to each othervia another tube that is similar to the tube 600 forming a channeltherein similar to the channel 700. This way, the workport 125 of theworksection 108 can be fluidly coupled to the workport fluid passage 170of the worksection 106.

FIG. 8 illustrates a perspective view of the worksection 106 having thetube 600 and a tube 800 mounted thereto, in accordance with an exampleimplementation. The tubes 600, 800 are mounted partially within theworksection 106 in their respective counterbores formed in theworksection 106. The worksection 108 can then be mounted to theworksection 106 and the tubes 600, 800 are inserted in their respectivecounterbores in the worksection 108 until the worksection 108 interfaceswith the worksection 106. The tube 800 is configured similar to the tube600 and is configured to have a channel 802 therein to fluidly couplethe workport fluid passage 170 to a workport fluid passage in theworksection 108 so as to fluidly couple the workport 123 to the workport125.

FIG. 9 illustrates a perspective cross-sectional view of the valveassembly 100 showing the tubes 600, 800, in accordance with an exampleimplementation. When the worksection 108 is assembled to the worksection106, the tube 600 at the interface between the worksections 106, 108 isconfigured to fluidly couple the workport 122 to the workport 124.Similarly, when the worksection 108 is assembled to the worksection 106,the tube 800 at the interface between the worksections 106, 108 isconfigured to fluidly couple the workport 123 to the workport 125.

With the configurations of FIGS. 4-9, the worksection 108 “duplicates”the workports 122, 123 of the worksection 106. The term “duplicate” isused herein to indicate that the fluid provided to the workport 122 isalso provided at the same pressure level to the workport 124, and thefluid provided to the workport 123 is also provided at the same pressurelevel to the workport 125. This way, the two boom actuators 206, 208 canbe driven in tandem. Fluidly coupling the workports 122, 124 and theworkports 123, 125 is implemented internally within the valve assembly100, rather than using complex ‘T’ fittings that split the fluidexternally.

As depicted in FIG. 9, the worksections 108 is thicker than theworksection 106 and, in addition to duplicating the workports 122, 123,it further includes oscillation control components integrated therein.This way, fluid exiting or entering the workports 122, 123, 124, 125 isnot split externally to be provided to an external, separate valve thathas the oscillation control components. Rather, the oscillation controlcomponents are integrated within the worksection 108 to avoid or reducethe use of fittings and hydraulic lines in the hydraulic system 200.

Oscillation control features can be used in mobile hydraulic machinery,such as a wheel loader, to improve ride quality on bumpy roads. Forexample, as a wheel loader with a heavy load goes over a bump, theweight from its bucket shifts up and down as pistons of the boomactuators 206, 208 oscillate back and forth, which causes the entiremachine to oscillate. Without oscillation control, to prevent materialfrom spilling out of the bucket, the wheel loader on a bumpy road wouldproceed slowly, which may be undesirable as it slows down siteoperations. Limiting oscillations of the boom actuators can renderoperating the wheel loader more comfortable to the operator, reducesstress on the wheel loader, saves time as the wheel loader can proceedwith a comparably higher speed, and can prevent spillage from thebucket.

In example implementations, an accumulator can be used to dampen changesin the force applied to the boom actuators 206, 208. An accumulator canbe considered a pressure storage reservoir in which hydraulic fluid isheld under pressure that is applied by an external source. The externalsource can be a spring or a compressed gas. An example accumulator caninclude a compressible gas (e.g., nitrogen) therein and an elasticdiaphragm or a piston, which separates the hydraulic fluid from asection of compressed gas beneath. While hydraulic fluid is incapable ofbeing substantially compressed under force, gas can be compressed, andcan thus absorb or dampen motion.

In examples, for the oscillation control system to operate, theoscillation control system can be configured to provide fluid connectionbetween the accumulator and the head sides of the boom actuators 206,208, i.e., between the accumulator and the workports 122, 124. Theoscillation control system can also be configured to provide aconnection between the source 202 of fluid (e.g., the pump) and theaccumulator so as to allow charging the accumulator with high pressurefluid to substantially equalize pressure level of fluid at the workports122, 124 (within head sides of the boom actuators 206, 208) and thepressure level of fluid in the accumulator. It may also be desirable forthe oscillation control system to provide a fluid connection between therod sides of the boom actuators 206, 208 and the tank 210 to lowerpressure level in the rod sides of the boom actuators 206, 208 undersome operating conditions.

Rather than providing the aforementioned fluid connections between theaccumulator, the source 202, the workports 122-125, the tank 210, etc.,via a separate valve and complex plumbing, the valve assembly 100provides oscillation control features integrated therein. Particularly,the worksection 108, which duplicates the workports 122, 123, alsoincludes oscillation control solenoid valves and connections toimplement oscillation control features without external plumbing. Thisconfiguration may reduce cost and complexity of the plumbing in thehydraulic system 200 and may enhance reliability of the hydraulic system200.

FIG. 10 illustrates a cutaway perspective view of a worksection showingoscillation control features, in accordance with an exampleimplementation. The cutaway shown in FIG. 10 can be of the monoblockworksection 400 shown in FIG. 4 or the worksection 108 shown in FIGS. 5,6, 9. In the description below, reference is made to the worksection108; however, it should be understood that the description andcomponents are equally applicable to the monoblock worksection 400.Hydraulic lines are represented schematically in FIG. 10 as dashed linesfor illustration.

The worksection 108 integrates oscillation control features therein.Beneficially, because the workports 124, 125 of the worksection 108 arefluidly coupled to the workports 122, 123, fluid from both of the boomactuators 206, 208 can be provided to and from the oscillation controlcomponents that are integrated with the worksection 108 without havingto route the fluid to an external valve having the oscillation controlcomponents and without the associated complex plumbing.

As depicted in FIG. 10, the hydraulic system 200 can include anaccumulator 1000 to control, limit, or dampen oscillations of thepistons of the boom actuators 206, 208. The worksection 108 can includea first solenoid-operated valve 1002 that has a first port 1004 fluidlycoupled to the source 202 and a second port 1006 fluidly coupled to theaccumulator 1000. When the first solenoid-operated valve 1002 isunactuated, fluid communication from the source 202 (e.g., a pump) tothe accumulator 1000 is blocked by the first solenoid-operated valve1002. When the first solenoid-operated valve 1002 is actuated, it opensa fluid path from the first port 1004 (from the source 202) to thesecond port 1006, then to the accumulator 1000 to charge the accumulator1000 with pressurized fluid from the source 202 until pressure level offluid in the accumulator 1000 reaches a particular desired pressurelevel.

Further, when the first solenoid-operated valve 1002 is actuated, fluidis provided to a load-sense (LS) passage 1008 to an opening 1010, whichis fluidly coupled to an inlet port of a LS shuttle (not shown). Theworksections 104, 106 include LS passages that, when a respective spoolof a respective worksection is actuated and pressurized fluid is provideto a respective actuator, a LS passage in the worksection becomesfluidly connected to a workport fluidly coupled to the actuator. Thus,the LS passage provides or transmits a pressure feedback signal from theworkport, and the pressure feedback signal can indicate the load on theactuator. As such, the pressure feedback signal can be referred to as aLS pressure fluid signal. The LS pressure fluid signal can indicate thefluid pressure required to drive the actuator.

When more than one worksection is actuated, (i.e., both spools of theworksections 104, 106 are actuated), both LS pressure fluid signals fromboth worksections are provided to respective inlet ports of one or moreLS shuttle valves that allows the LS pressure fluid signal with thehigher pressure level to pass through to an outlet port of the LSshuttle, while blocking the other LS pressure fluid signal. The LSpressure fluid signal that has the higher pressure level is thenprovided from the outlet port of a LS shuttle valve to a LS port of aload-sensing source of pressurized fluid, e.g., the source 202. Anexample load-sensing source of pressurized fluid includes a load-sensingvariable displacement pump. The source 202 is configured to provideenough fluid flow at a pressure level that is equal to the pressurelevel of the LS pressure fluid signal plus a margin pressure value. Forexample, if a pressure level of the LS pressure fluid signal is 2000psi, the source 202 can provide fluid flow at a pressure level of 2000psi plus a margin pressure value (e.g., 200 psi), and thus the fluid canhave a pressure of about 2200 psi. In other words, pressure level ofpressurized fluid provided by the source 202 is based on the LS pressuresignal

When none of the actuators 204, 206, or 208 is commanded to move, thespools of the worksections are not actuated, and the LS passages in theworksections 104, 106 are not fluidly coupled to the respectiveworkports. In this case, the source 202 does not receive a load-sensepressure signal. As a result, the source 202 operates in a standby modeof operation where minimal fluid flow is provided at a low pressurelevel, e.g., at the margin pressure value of 200-300 psi.

To enable the source 202 to provide high pressure fluid to theaccumulator 1000, the LS passage 1008 provides a pressure signal fromthe second port 1006 of the first solenoid-operated valve 1002, when thefirst solenoid-operated valve 1002 is actuated, to a LS shuttle valve.If none of the worksections 104, 106 is actuated, the LS shuttle valvecan pass through the pressure signal from the LS passage 1008 to an LSport of the source 202. The source 202 then provides fluid at a pressurelevel equal to the pressure level in the LS passage 1008 plus a marginpressure. Thus, fluid at the first port 1004 increases and pressurelevel in the LS passage 1008, causing the source 202 to provide fluid atan even higher pressure level. As such, the source 202 “chases” itselfand provides fluid to the accumulator 1000 at an increasingly higherpressure level. When the pressure level at the accumulator 1000 reachesa desired pressure level, the first solenoid-operated valve 1002 can bedeactivated to block fluid flow from the first port 1004 to the secondport 1006. As a result, the source 202 can go back to a standby mode asno pressure signal is provided to its LS port via the LS passage 1008.

To dampen oscillations of the boom actuators 206, 208, the worksection108 is configured to allow fluid communication between the head sides ofthe boom actuators 206, 208 (i.e., between the workports 122, 124) andthe accumulator 1000 under some operating conditions. The worksection108 includes a second solenoid-operated valve 1012 that has a first port1013, which is fluidly coupled to the workport 124 via fluid passages1014, 1016, 1018 formed in the worksection 108.

The worksection 108 further includes a pilot-operated valve 1020. Thepilot-operated valve 1020 can be a normally-closed spool-type logicelement, for example. The pilot-operated valve 1020 can have threeports: (i) a first port 1022 that is fluidly coupled to a second port1024 of the second solenoid-operated valve 1012 via fluid passage 1025,(ii) a second port 1026 that is fluidly coupled to the accumulator 1000via fluid passage 1028, which is fluidly coupled to an accumulator portto which the accumulator 1000 is fluidly coupled, and (iii) a third port1030 that is fluidly coupled to the workport 124 (which is fluidlycoupled to head sides of the boom actuators 206, 208) via the fluidpassage 1014.

The pilot-operated valve 1020 has a movable element (e.g., a spool)that, when the pilot-operated valve 1020 is unactuated, blocks fluidflow between the second port 1026 and the third port 1030. The firstport 1022 operates a pilot port, and when a a pressurized fluid signal(i.e., a pilot signal) is provided to the first port 1022 of thepilot-operated valve 1020, the pilot-operated valve 1020 is actuated andits movable element (e.g., its spool) can move (e.g., upward in FIG. 10)to open a fluid path between the second port 1026 and the third port1030.

The second solenoid-operated valve 1012 controls actuation or the stateof the pilot-operated valve 1020. Particularly, when the secondsolenoid-operated valve 1012 is unactuated, no pressure fluid signal isprovided to the first port 1022 of the pilot-operated valve 1020.Conversely, when the second solenoid-operated valve 1012 is actuated, apressure fluid signal (i.e., a pilot signal) is provided from the firstport 1013 (which is fluidly coupled to the workport 124 via the fluidpassages 1014, 1016, 1018) to the second port 1024 and then to the firstport 1022 of the pilot-operated valve 1020 via the fluid passage 1025.As a result of the pilot signal provided to the first port 1022, thepilot-operated valve 1020 is actuated, and a fluid path is opened toallow fluid flow between the accumulator 1000 and the workport 124.

The fluid path comprises the fluid passage 1028, the second port 1026 ofthe pilot-operated valve 1020, the third port 1030 of the pilot-operatedvalve 1020, and the fluid passage 1014. The fluid path allows fluid flowfrom the accumulator 1000 to the workport 124 or from the workport 124to the accumulator 1000. Because the workport 124 is fluidly coupled tothe head sides of the boom actuators 206, 208, actuating the secondsolenoid-operated valve 1012 allows for fluid communication between thehead sides of the boom actuators 206, 208 and the accumulator 1000.

Further under some operating conditions, it may be desirable to ventfluid in the rod sides of the boom actuators 206, 208 to the tank 210.The worksection 108 can include a third solenoid-operated valve 1032having a first port 1034 and a second port 1036. The first port 1034 isfluidly coupled to the workport 125 (which is fluidly coupled to the rodsides of the boom actuators 206, 208). In an example, the first port1034 is fluidly coupled to the workport 125 via cross-drilled fluidpassages (not shown) formed in the worksection 108. The second port 1036is fluidly coupled to a tank passage 1038, which is fluidly coupled tothe tank 210.

When the third solenoid-operated valve 1032 is unactuated, it blocksfluid flow between the first port 1034 and the second port 1036, andthus blocks fluid flow between the workport 125 and the tank 210. Whenthe third solenoid-operated valve 1032 is actuated, it opens a fluidpath from the second port 1036 to the first port 1034, and thereforeprovides a fluid path from the workport 125 to the tank 210 via thesecond port 1036, the first port 1034, and the tank passage 1038.

With this configuration, the worksection 108 integrates components thatcan enable controlling (e.g., limiting or dampening) oscillations of theboom actuators 206, 208. The components can be fluidly coupled to theboom actuators 206, 208, the source 202, and the tank 210 to selectivelyallow fluid communication therebetween without requiring complexfittings and external plumbing. An electronic controller (e.g.,microprocessor) of the hydraulic system can then provide electriccommand signals to various components (e.g., the solenoid-operated valve1002, the pilot-operated valve 1020, and the solenoid-operated valve1032) in a particular sequence and at particular times during operationof the hydraulic machine to dampen oscillations of the boom actuators206, 208.

FIG. 11 is a flowchart of a method 1100 for operating a hydraulicsystem, in accordance with an example implementation. The method 1100shown in FIG. 11 presents an example of a method that could be used withthe valve assembly 100 and the hydraulic system 200 shown throughout theFigures, for example. The method 1100 may include one or moreoperations, functions, or actions as illustrated by one or more ofblocks 1102-1104. Although the blocks are illustrated in a sequentialorder, these blocks may also be performed in parallel, and/or in adifferent order than those described herein. Also, the various blocksmay be combined into fewer blocks, divided into additional blocks,and/or removed based upon the desired implementation. It should beunderstood that for this and other processes and methods disclosedherein, flowcharts show functionality and operation of one possibleimplementation of present examples. Alternative implementations areincluded within the scope of the examples of the present disclosure inwhich functions may be executed out of order from that shown ordiscussed, including substantially concurrent or in reverse order,depending on the functionality involved, as would be understood by thosereasonably skilled in the art.

At block 1102, the method 1100 includes shifting a spool (e.g., thespool 148) axially in a first axial direction within a bore of the valveassembly 100 (e.g., by actuating the pilot valve 129), wherein the valveassembly 100 comprises: (i) a first workport (e.g., the workport 122)fluidly coupled to a first chamber (e.g., head side) of a first actuator(e.g., the first boom actuator 206), (ii) a second workport (e.g., theworkport 123) fluidly coupled to a second chamber (e.g., rod side) ofthe first actuator (e.g., the first boom actuator 206), (iii) a thirdworkport (e.g., the workport 124) fluidly coupled to a third chamber(e.g., head side) of a second actuator (e.g., the second boom actuator208), wherein the third workport is fluidly coupled to the firstworkport via a first fluid passage (e.g., the fluid passage 402, or thefluid conduit 500), (iv) a fourth workport (e.g., the workport 125)fluidly coupled to a fourth chamber (e.g., rod side) of the secondactuator (e.g., the second boom actuator 208), wherein the fourthworkport is fluidly coupled to the second workport via a second fluidpassage, and wherein shifting the spool in the first axial directioncauses pressurized fluid to be provided from the source 202 ofpressurized fluid to the first workport and to the third workport viathe first fluid passage so as to drive the first actuator and the secondactuator in tandem in a first direction (e.g., extend the pistons of theboom actuators 206, 208).

At block 1104, the method 1100 includes shifting the spool in a secondaxial direction opposite the first axial direction (e.g., by actuatingthe pilot valve 128), thereby causing pressurized fluid to be providedfrom the source 202 of pressurized fluid to the second workport and tothe fourth workport via the second fluid passage so as to drive thefirst actuator and the second actuator in tandem in a second direction(e.g., retract the pistons of the boom actuators 206, 208) opposite thefirst direction.

The detailed description above describes various features and operationsof the disclosed systems with reference to the accompanying figures. Theillustrative implementations described herein are not meant to belimiting. Certain aspects of the disclosed systems can be arranged andcombined in a wide variety of different configurations, all of which arecontemplated herein.

Further, unless context suggests otherwise, the features illustrated ineach of the figures may be used in combination with one another. Thus,the figures should be generally viewed as component aspects of one ormore overall implementations, with the understanding that not allillustrated features are necessary for each implementation.

Additionally, any enumeration of elements, blocks, or steps in thisspecification or the claims is for purposes of clarity. Thus, suchenumeration should not be interpreted to require or imply that theseelements, blocks, or steps adhere to a particular arrangement or arecarried out in a particular order.

Further, devices or systems may be used or configured to performfunctions presented in the figures. In some instances, components of thedevices and/or systems may be configured to perform the functions suchthat the components are actually configured and structured (withhardware and/or software) to enable such performance. In other examples,components of the devices and/or systems may be arranged to be adaptedto, capable of, or suited for performing the functions, such as whenoperated in a specific manner.

By the term “substantially” or “about” it is meant that the recitedcharacteristic, parameter, or value need not be achieved exactly, butthat deviations or variations, including for example, tolerances,measurement error, measurement accuracy limitations and other factorsknown to skill in the art, may occur in amounts that do not preclude theeffect the characteristic was intended to provide

The arrangements described herein are for purposes of example only. Assuch, those skilled in the art will appreciate that other arrangementsand other elements (e.g., machines, interfaces, operations, orders, andgroupings of operations, etc.) can be used instead, and some elementsmay be omitted altogether according to the desired results. Further,many of the elements that are described are functional entities that maybe implemented as discrete or distributed components or in conjunctionwith other components, in any suitable combination and location.

While various aspects and implementations have been disclosed herein,other aspects and implementations will be apparent to those skilled inthe art. The various aspects and implementations disclosed herein arefor purposes of illustration and are not intended to be limiting, withthe true scope being indicated by the following claims, along with thefull scope of equivalents to which such claims are entitled. Also, theterminology used herein is for the purpose of describing particularimplementations only, and is not intended to be limiting.

What is claimed is:
 1. A valve assembly comprising: a monoblockworksection configured to control fluid flow to and from a firstactuator and a second actuator configured to be actuated in tandem,wherein the monoblock worksection comprises: (i) a first workportconfigured to be fluidly coupled to a first chamber of the firstactuator, (ii) a second workport configured to be fluidly coupled to asecond chamber of the first actuator, (iii) a third workport configuredto be fluidly coupled to a third chamber of the second actuator, whereinthe third workport is fluidly coupled to the first workport via a firstfluid passage within the monoblock worksection, and (iv) a fourthworkport configured to be fluidly coupled to a fourth chamber of thesecond actuator, wherein the fourth workport is fluidly coupled to thesecond workport via a second fluid passage within the monoblockworksection; and a spool axially movable in a bore within the monoblockworksection, wherein: (i) when the spool is shifted axially in a firstaxial direction within the bore, pressurized fluid is provided from asource of pressurized fluid to the first workport and to the thirdworkport via the first fluid passage so as to drive the first actuatorand the second actuator in tandem in a first direction, and (ii) whenthe spool is shifted axially in a second axial direction within the boreopposite the first axial direction, pressurized fluid is provided fromthe source of pressurized fluid to the second workport and to the fourthworkport via the second fluid passage so as to drive the first actuatorand the second actuator in tandem in a second direction opposite thefirst direction.
 2. The valve assembly of claim 1, wherein the monoblockworksection further comprises: a solenoid-operated valve having a firstport and a second port, wherein the first port is configured to befluidly coupled to the source of pressurized fluid, wherein the secondport is configured to be fluidly coupled to an accumulator, wherein whenthe solenoid-operated valve is actuated, a fluid path is formed thereinto allow fluid flow between the first port and the second port so as toallow the accumulator to be charged with pressurized fluid from thesource of pressurized fluid.
 3. The valve assembly of claim 2, whereinthe source of pressurized fluid is a load-sensing source, and whereinthe valve assembly further comprises: a load-sense shuttle valve having:(i) an inlet port that is fluidly coupled to the second port of thesolenoid-operated valve, and (ii) an outlet port configured to befluidly coupled to a load-sense port of the load-sensing source, whereinwhen the solenoid-operated valve is actuated, a pressure fluid signal isprovided from the source of pressurized fluid through the first port ofthe solenoid-operated valve to the second port of the solenoid-operatedvalve, to the inlet port of the load-sense shuttle valve, to the outletport of the load-sense shuttle valve, then to the load-sense port of thesource of pressurized fluid, wherein pressure level of pressurized fluidof the load-sensing source is based on the pressure fluid signal.
 4. Thevalve assembly of claim 1, wherein the monoblock worksection furthercomprises: a solenoid-operated valve having a first port and a secondport, wherein the first port of the solenoid-operated valve isconfigured to be fluidly coupled to the second workport and the fourthworkport of the monoblock worksection, wherein the second port of thesolenoid-operated valve is configured to be fluidly coupled to a tank,wherein when the solenoid-operated valve is actuated, a fluid path isformed therein to allow fluid flow between the first port and the secondport so as to allow fluid from the second chamber of the first actuatorand fluid from the fourth chamber of the second actuator to flow to thetank.
 5. The valve assembly of claim 1, wherein the monoblockworksection further comprises: a solenoid-operated valve having a firstport and a second port, wherein the first port of the solenoid-operatedvalve is fluidly coupled to the first workport and the third workport ofthe monoblock worksection via a fluid passage within the monoblockworksection; and a pilot-operated valve having a first respective port,a second respective port, and a third port, wherein first respectiveport of the pilot-operated valve is fluidly coupled to the second portof the solenoid-operated valve, wherein the second respective port ofthe pilot-operated valve is configured to be fluidly coupled to anaccumulator, and wherein the third port of the pilot-operated valve isfluidly coupled to the first workport and the third workport of themonoblock worksection, wherein when the solenoid-operated valve isactuated, a fluid path is formed therein to allow fluid to flow from thefirst port to the second port and then to the first respective port ofthe pilot-operated valve, thereby actuating the pilot-operated valve andallowing fluid flow between the second respective port and the thirdport so as to fluidly couple the accumulator to the first workport andthe third workport of the monoblock worksection.
 6. A valve assemblycomprising: a first worksection configured to control fluid flow to andfrom a first actuator and a second actuator configured to be actuated intandem, wherein the first worksection comprises: (i) a first workportconfigured to be fluidly coupled to a first chamber of the firstactuator, (ii) a second workport configured to be fluidly coupled to asecond chamber of the first actuator; a second worksection mounted tothe first worksection, wherein the second worksection comprises: (i) athird workport configured to be fluidly coupled to a third chamber ofthe second actuator, wherein the third workport is fluidly coupled tothe first workport via a first fluid conduit, and (ii) a fourth workportconfigured to be fluidly coupled to a fourth chamber of the secondactuator, wherein the fourth workport is fluidly coupled to the secondworkport via a second fluid conduit; and a spool axially movable in abore within the first worksection, wherein: (i) when the spool isshifted axially in a first axial direction within the bore, pressurizedfluid is provided from a source of pressurized fluid to the firstworkport and to the third workport via the first fluid conduit so as todrive the first actuator and the second actuator in tandem in a firstdirection, and (ii) when the spool is shifted axially in a second axialdirection within the bore opposite the first axial direction,pressurized fluid is provided from the source of pressurized fluid tothe second workport and to the fourth workport via the second fluidconduit so as to drive the first actuator and the second actuator intandem in a second direction opposite the first direction.
 7. The valveassembly of claim 6, wherein the first fluid conduit comprises a firstfluid passage formed in the first worksection and a second fluid passagein the second worksection, wherein the first fluid passage is alignedwith the second fluid passage to form the first fluid conduit.
 8. Thevalve assembly of claim 6, wherein the first worksection comprises anannular groove formed on an end face of the first worksection that facesthe second worksection, wherein the annular groove is formed around thefirst fluid conduit, wherein the valve assembly further comprises: aface seal disposed in the annular groove of the first worksection. 9.The valve assembly of claim 6, further comprising: a first tube disposedin the first fluid conduit at an interface between the first worksectionand the second worksection; and a second tube disposed in the secondfluid conduit at the interface between the first worksection and thesecond worksection.
 10. The valve assembly of claim 9, wherein each ofthe first tube and the second tube comprises: a first annular grooveformed in an exterior peripheral surface of a respective tube; a firstradial seal disposed in the first annular groove, wherein the firstradial seal is disposed between an interior peripheral surface of thefirst worksection and the exterior peripheral surface of the respectivetube; a second annular groove formed in the exterior peripheral surfaceof the respective tube; and a second radial seal disposed in the secondannular groove, wherein the second radial seal is disposed between aninterior peripheral surface of the second worksection and the exteriorperipheral surface of the respective tube.
 11. The valve assembly ofclaim 6, wherein the second worksection further comprises: asolenoid-operated valve having a first port and a second port, whereinthe first port is configured to be fluidly coupled to the source ofpressurized fluid, wherein the second port is configured to be fluidlycoupled to an accumulator, wherein when the solenoid-operated valve isactuated, a fluid path is formed therein to allow fluid flow between thefirst port and the second port so as to allow the accumulator to becharged with pressurized fluid from the source of pressurized fluid. 12.The valve assembly of claim 6, wherein the second worksection furthercomprises: a solenoid-operated valve having a first port and a secondport, wherein the first port of the solenoid-operated valve isconfigured to be fluidly coupled to the second workport of the firstworksection and the fourth workport of the second worksection, whereinthe second port of the solenoid-operated valve is configured to befluidly coupled to a tank, wherein when the solenoid-operated valve isactuated, a fluid path is formed therein to allow fluid flow between thefirst port and the second port so as to allow fluid from the secondchamber of the first actuator and fluid from the fourth chamber of thesecond actuator to flow to the tank.
 13. The valve assembly of claim 6,wherein the second worksection further comprises: a solenoid-operatedvalve having a first port and a second port, wherein the first port ofthe solenoid-operated valve is fluidly coupled to the first workport ofthe first worksection and the third workport of the second worksectionvia a fluid passage within the second worksection; and a pilot-operatedvalve having a first respective port, a second respective port, and athird port, wherein first respective port of the pilot-operated valve isfluidly coupled to the second port of the solenoid-operated valve,wherein the second respective port of the pilot-operated valve isconfigured to be fluidly coupled to an accumulator, and wherein thethird port of the pilot-operated valve is fluidly coupled to the firstworkport of the first worksection and the third workport of the secondworksection, wherein when the solenoid-operated valve is actuated, afluid path is formed therein to allow fluid to flow from the first portto the second port and then to the first respective port of thepilot-operated valve, thereby actuating the pilot-operated valve andallowing fluid flow between the second respective port and the thirdport so as to fluidly couple the accumulator to the first workport ofthe first worksection and the third workport of the second worksection.14. A hydraulic system comprising: a source of pressurized fluid; atank; a first actuator having a first chamber and a second chamber; asecond actuator having a third chamber and a fourth chamber, andconfigured to be actuated in tandem with the first actuator; and a valveassembly fluidly coupled to the source of pressurized fluid, the tank,the first actuator, and the second actuator, wherein the valve assemblycomprises: a first workport fluidly coupled to the first chamber of thefirst actuator, a second workport fluidly coupled to the second chamberof the first actuator, a third workport fluidly coupled to the thirdchamber of the second actuator, wherein the third workport is fluidlycoupled to the first workport via a first fluid passage, a fourthworkport fluidly coupled to the fourth chamber of the second actuator,wherein the fourth workport is fluidly coupled to the second workportvia a second fluid passage, and a spool axially movable in a bore withinthe valve assembly, wherein: (i) when the spool is shifted axially in afirst axial direction within the bore, pressurized fluid is providedfrom the source of pressurized fluid to the first workport and to thethird workport via the first fluid passage so as to drive the firstactuator and the second actuator in tandem in a first direction, and(ii) when the spool is shifted axially in a second axial directionwithin the bore opposite the first axial direction, pressurized fluid isprovided from the source of pressurized fluid to the second workport andto the fourth workport via the second fluid passage so as to drive thefirst actuator and the second actuator in tandem in a second directionopposite the first direction.
 15. The hydraulic system of claim 14,wherein the valve assembly comprises: a monoblock worksection comprisingthe first workport, the second workport, the third workport, and thefourth workport, wherein the first fluid passage and the second fluidpassage are formed within the monoblock worksection, and wherein thebore in which the spool is axially movable is formed within themonoblock worksection.
 16. The hydraulic system of claim 14, wherein thevalve assembly comprises: a first worksection configured to controlfluid flow to and from the first actuator and the second actuator,wherein the first worksection comprises the first workport, the secondworkport, and the bore in which the spool is axially movable; and asecond worksection mounted to the first worksection, wherein the secondworksection comprises the third workport and the fourth workport. 17.The hydraulic system of claim 16, wherein the first worksectioncomprises an annular groove formed on an end face of the firstworksection that faces the second worksection, wherein the annulargroove is formed around the first fluid passage, wherein the valveassembly further comprises: a face seal disposed in the annular grooveof the first worksection.
 18. The hydraulic system of claim 16, whereinthe valve assembly further comprises: a first tube disposed in the firstfluid passage at an interface between the first worksection and thesecond worksection; and a second tube disposed in the second fluidpassage at the interface between the first worksection and the secondworksection.
 19. The hydraulic system of claim 18, wherein each of thefirst tube and the second tube comprises: a first annular groove formedin an exterior peripheral surface of a respective tube; a first radialseal disposed in the first annular groove, wherein the first radial sealis disposed between an interior peripheral surface of the firstworksection and the exterior peripheral surface of the respective tube;a second annular groove formed in the exterior peripheral surface of therespective tube; and a second radial seal disposed in the second annulargroove, wherein the second radial seal is disposed between an interiorperipheral surface of the second worksection and the exterior peripheralsurface of the respective tube.
 20. The hydraulic system of claim 14,further comprising: an accumulator, wherein the valve assembly furthercomprises a solenoid-operated valve having a first port and a secondport, wherein the first port is fluidly coupled to the source ofpressurized fluid, wherein the second port is fluidly coupled to theaccumulator, wherein when the solenoid-operated valve is actuated, afluid path is formed therein to allow fluid flow between the first portand the second port so as to allow the accumulator to be charged withpressurized fluid from the source of pressurized fluid.
 21. Thehydraulic system of claim 14, wherein the valve assembly furthercomprises: a solenoid-operated valve having a first port and a secondport, wherein the first port of the solenoid-operated valve is fluidlycoupled to the second workport and the fourth workport, wherein thesecond port of the solenoid-operated valve is fluidly coupled to thetank, wherein when the solenoid-operated valve is actuated, a fluid pathis formed therein to allow fluid flow between the first port and thesecond port so as to allow fluid from the second chamber of the firstactuator and fluid from the fourth chamber of the second actuator toflow to the tank.
 22. The hydraulic system of claim 14, furthercomprising: an accumulator, wherein the valve assembly furthercomprises: a solenoid-operated valve having a first port and a secondport, wherein the first port of the solenoid-operated valve is fluidlycoupled to the first workport and the third workport via a fluid passagewithin the valve assembly, and a pilot-operated valve having a firstrespective port, a second respective port, and a third port, whereinfirst respective port of the pilot-operated valve is fluidly coupled tothe second port of the solenoid-operated valve, wherein the secondrespective port of the pilot-operated valve is fluidly coupled to theaccumulator, and wherein the third port of the pilot-operated valve isfluidly coupled to the first workport and the third workport, whereinwhen the solenoid-operated valve is actuated, a fluid path is formedtherein to allow fluid to flow from the first port to the second portand then to the first respective port of the pilot-operated valve,thereby actuating the pilot-operated valve and allowing fluid flowbetween the second respective port and the third port so as to fluidlycouple the accumulator to the first workport and the third workport.